KR102384051B1 - A control system and method for an HVAC unit, and a medium containing such processor-executable instructions - Google Patents

Abstract

The present invention relates to a vapor compression system (72) having a refrigerant, a compressor (74) of a vapor compression system (72) configured to circulate the refrigerant through the vapor compression system (72), Expansion device 78 of vapor compression system 72 configured to regulate flow, and a measured amount of superheat of refrigerant entering compressor 74 reaches a target amount of superheat, or refrigerant leaving compressor 74 The measured amount of superheat of refrigerant entering compressor 74, the measured outlet temperature of refrigerant leaving compressor 74, or these A heating, ventilation and air conditioning (HVAC) system (10) comprising a controller (104) configured to adjust a position of an inflation device (78) based on a combination of

Description

A control system and method for an HVAC unit, and a medium containing such processor-executable instructions

FIELD OF THE INVENTION The present invention relates generally to heating, ventilation and cooling systems. In particular, the present invention relates to a system and method for controlling an electronic expansion valve (EEV) in a vapor compression system.

A wide range of applications exist for heating, ventilation and air conditioning (HVAC) systems. For example, residential, commercial and industrial systems are used to control temperature and air in residential areas and buildings using fluids such as refrigerants. HVAC systems can circulate refrigerant through a closed loop between an evaporator where the refrigerant absorbs heat and a condenser where the refrigerant dissipates heat. As an example, the refrigerant may absorb heat from the first fluid and transfer heat to the second fluid, ultimately cooling the first fluid and/or heating the second fluid. The refrigerant evaporates into a vapor by absorbing heat from the first fluid as it flows through the evaporator. The compressor then compresses the vapor such that the pressure and/or temperature of the vapor rises for subsequent cooling by the second fluid in the condenser, transferring heat from the first fluid to the second fluid.

In some cases, the vapor is superheated at the inlet of the compressor to ensure that the refrigerant is in vapor state before entering the compressor. To control the amount of superheat of the refrigerant entering the compressor, existing systems include a liquid injection device that cools the vapor within the compressor. For example, the liquid injection device injects liquid refrigerant droplets into or at the inlet of the compressor to adjust the amount of superheat of the vapor entering the compressor and/or the temperature of the vapor exiting the compressor. Unfortunately, the liquid injection device comprises additional components (eg, in particular piping, pumps, nozzles) for injecting liquid refrigerant into the compressor. In addition, injecting liquid refrigerant into the compressor may reduce the performance of the compressor and, thus, the performance of the HVAC system.

In one embodiment, a heating, ventilation, and air conditioning (HVAC) system is a vapor compression system having a refrigerant, a compressor of the vapor compression system configured to circulate the refrigerant through the vapor compression system, and regulating the flow of refrigerant through the vapor compression system an expansion device of a vapor compression system configured to: and the measured amount of superheat of the refrigerant entering the compressor reaches a target amount of superheat, or the measured discharge temperature of the refrigerant leaving the compressor reaches the target discharge temperature, or these and a controller configured to adjust the position of the expansion device based on the measured amount of superheat of the refrigerant entering the compressor, the measured discharge temperature of the refrigerant leaving the compressor, or a combination thereof to be a combination of:

In another embodiment, one or more tangible, non-transitory machine readable media receive first feedback indicative of a temperature and pressure of refrigerant entering a compressor of the vapor compression system, the refrigerant entering the compressor of the vapor compression system determine a measured amount of superheat of refrigerant entering the compressor of the vapor compression system using the temperature and pressure of a measured amount of superheat of refrigerant entering the compressor, discharge temperature of refrigerant leaving the compressor, or and processor-executable instructions for adjusting a position of an expansion device of the vapor compression system based on a combination thereof.

In another embodiment, a method includes receiving a first feedback indicative of a temperature and pressure of a refrigerant entering a compressor of the vapor compression system, wherein the temperature and pressure of the refrigerant entering a compressor of the vapor compression system are used to control the vapor compression system. determining a measured amount of superheat of refrigerant entering the compressor, receiving second feedback indicative of an outlet temperature of refrigerant leaving the compressor of the vapor compression system, and that the refrigerant entering the compressor reaches a target amount of overheat vapor compression based on the measured amount of superheat of the refrigerant entering the compressor, the discharge temperature of the refrigerant leaving the compressor, or a combination thereof, such that the refrigerant leaving the compressor reaches a target discharge temperature, or a combination thereof. adjusting the position of the inflation device of the system.

1 is a schematic diagram of environmental control for management of a building environment that may employ one or more HVAC units in accordance with an aspect of the present invention.
FIG. 2 is a schematic diagram of a vapor compression system that may be utilized in the HVAC unit of FIG. 1 in accordance with an aspect of the present invention;
3 is a schematic diagram of the vapor compression system of FIG. 2 in accordance with an aspect of the present invention;
4 is a block diagram of a process that may be utilized to adjust the electronic expansion valve of the vapor compression system of FIGS. 2 and 3 in accordance with an aspect of the present invention.

Embodiments of the present invention provide an expansion device (eg, discharge temperature) to control the amount of superheat of the refrigerant entering the compressor (eg suction superheat) and/or the temperature of the refrigerant exiting the compressor (eg discharge temperature). For example, it relates to a heating, ventilation and air conditioning (HVAC) system that adjusts the position of an electronic expansion valve (EEV). According to embodiments of the present invention, an HVAC system includes one or more control devices configured to adjust the position of the expansion device to control intake overheating and/or exhaust temperature. As previously discussed, existing HVAC systems utilize a liquid injection device that injects liquid refrigerant droplets into a compressor. Unfortunately, the liquid injection device utilizes additional components that increase the cost of the HVAC system. In addition, liquid injection devices reduce the performance of the compressor as a result of liquid refrigerant droplets coming into contact with the moving components of the compressor.

Thus, adjusting the expansion device to control the suction overheating and/or discharge temperature of the compressor can eliminate the liquid injection device in the HVAC system and improve the performance of the compressor. In some embodiments, the inflation device is controlled using a first control module (eg, intake superheat module) under operating parameters of a first set of HVAC system, and wherein the inflation device is operated under a first set of operating parameters of the HVAC system. The parameters are controlled using a second control module (eg exhaust temperature module). For example, the first control module may be configured to enter the compressor during starting conditions (eg, for a predetermined amount of time upon initiating operation of the compressor) and/or (eg, the pressure and temperature of the refrigerant). determined from) when the amount of superheat of the refrigerant exceeds the first threshold. In addition, the second control module may be utilized when the temperature of the refrigerant discharged from the compressor exceeds the second threshold. In certain embodiments, the HVAC system includes a first controller (eg, a first proportional, integral, derivative (PID) controller) including a first control module and a second controller (eg, a second control module) including a second control module. For example, a second PID controller). In other embodiments, the HVAC system includes a single controller (eg, a PID controller) that includes both a first control module and a second control module. In any case, the expansion device is adjusted based on the amount of superheat of the refrigerant flowing into the compressor (eg suction superheat) and the temperature of the refrigerant exiting the compressor (eg discharge temperature). Accordingly, the temperature of the refrigerant is controlled without injecting liquid droplets into the compressor, increasing the efficiency of the compressor and/or HVAC system.

Referring now to the drawings, FIG. 1 is a perspective view of one embodiment of an environment for a heating, ventilation, air conditioning and refrigeration (HVAC&R) system 10 in a building 12 for a typical commercial environment. The HVAC&R system 10 may include a vapor compression system 14 that supplies a cooled liquid that may be used to cool the building 12 . The HVAC&R system 10 may include a boiler 16 that supplies warm liquid to heat the building 12 and an air distribution system that circulates air through the building 12 . The air distribution system may include an air return duct 18 , an air supply duct 20 and/or an air handler 22 . In some embodiments, air handler 22 may include a heat exchanger coupled to boiler 16 and vapor compression system 14 by conduits 24 . The heat exchanger in air handler 22 may receive either heated liquid from boiler 16 or cooled liquid from vapor compression system 14 depending on the mode of operation of HVAC&R system 10 . Although the HVAC&R system 10 is shown having a separate air handler on each floor of the building 12 , in other embodiments, the HVAC&R system 10 includes air handlers 22 that may be shared between floors. and/or other components.

2 is an embodiment of a vapor compression system 72 that may be used in the HVAC unit 12 described above. Vapor compression system 72 may circulate refrigerant through refrigerant loop 73 beginning with compressor 74 . The circuit may also include a condenser 76 , an expansion valve(s) or device(s) 78 , and an evaporator 80 . The vapor compression system 72 further includes a control panel 82 having an analog-to-digital (A/D) converter 84 , a microprocessor 86 , a non-volatile memory 88 and/or an interface board 90 . can do. Control panel 82 and components of control panel 82 function to regulate operation of vapor compression system 72 based on feedback from an operator, sensors of vapor compression system 72 detecting operating conditions, and the like. can do.

In some embodiments, the vapor compression system 72 includes variable speed drives (VSDs) 92 , a motor 94 , a compressor 74 , a condenser 76 , an expansion valve or device 78 , and/or an evaporator ( 80) may be used. Motor 94 may drive compressor 74 and may be powered by a variable speed drive (VSD) 92 . VSD 92 receives alternating current (AC) power having a specific fixed line voltage and fixed line frequency from an AC power source, and provides power with variable voltage and frequency to motor 94 . In other embodiments, the motor 94 may be powered directly from an AC or direct current (DC) power source. Motor 94 includes any type of electric motor that can be powered by a VSD or directly from an AC or DC power source, such as a switched reluctance motor, an induction motor, an electronically commutated permanent magnet motor, or other suitable motor. can do.

Compressor 74 compresses the refrigerant vapor and delivers the vapor to condenser 76 through a discharge passage. In some embodiments, compressor 74 may be a centrifugal compressor. Refrigerant vapor delivered by compressor 74 to condenser 76 may transfer heat to a fluid passing across condenser 76 , such as ambient or environmental air 96 . Refrigerant vapor may condense into a refrigerant liquid in condenser 76 as a result of thermal heat transfer with ambient air 96 . Liquid refrigerant from condenser 76 may flow through expansion device 78 to evaporator 80 .

Liquid refrigerant delivered to evaporator 80 may absorb heat from other air streams, such as feed air stream 98 provided to building 12 or residential area 52 . For example, feed air stream 98 may include ambient or environmental air, return air from a building, or a combination of both. The liquid refrigerant in the evaporator 80 may undergo a phase change from liquid refrigerant to refrigerant vapor. In this way, the evaporator 38 may reduce the temperature of the feed air stream 98 through thermal heat transfer with the refrigerant. Thereafter, the vapor refrigerant exits the evaporator 80 and returns to the compressor 74 by a suction line to complete circulation.

In some embodiments, vapor compression system 72 may further include a reheat coil in addition to evaporator 80 . For example, a reheat coil may be located downstream of the evaporator with respect to the feed air stream 98 , and before the feed air stream 98 is directed to the building 12 or residential area 52 , the feed air stream 98 . ) is supercooled to remove moisture from the feed air stream 98 , the feed air stream 98 may be reheated.

It should be understood that any of the features described herein may be integrated with the HVAC unit 12 , the residential heating and cooling system 50 , or other HVAC systems. Moreover, while the features disclosed herein are described in the context of embodiments that directly heat and cool a feed air stream provided to a building or other load, embodiments of the present invention may also be applicable to other HVAC systems. For example, features described herein may be applied to mechanical cooling systems, free cooling systems, cooling device systems, or other heat pump or refrigeration applications.

As discussed above, in some embodiments, expansion device 78 is an electronic expansion valve (EEV) that can be adjusted to control the temperature of the refrigerant entering and/or exiting compressor 74 . Existing systems utilize a liquid injection system to control the temperature of the refrigerant in the compressor 74 . Unfortunately, liquid injection systems can reduce the efficiency of compressor 74 and/or HVAC unit 12 . Accordingly, embodiments of the present invention provide a first control module (eg, intake superheat module) under a first set of operating parameters of an HVAC system, and a second control module under a second set of operating parameters of an HVAC system. control of the expansion device 78 using (eg, an exhaust temperature module). For example, the first control module may determine that the temperature of the refrigerant entering the compressor 74 and/or during start-up conditions (eg, for a predetermined amount of time upon initiating operation of the compressor 74 ) and/or It may be utilized when the first threshold is exceeded. In addition, the second control module may be utilized when the temperature of the refrigerant discharged from the compressor 74 exceeds the second threshold.

FIG. 3 shows control circuitry 100 that may be used to control the operation of the expansion device 78 in the vapor compression system 72 described in FIG. 2 . The location of the expansion device 78 depends on the amount of superheat of refrigerant entering the compressor 74 (eg, the suction port of the compressor 74 ) and/or the amount of superheat of the compressor 74 (eg, the suction port of the compressor 74 ). can be adjusted based on the temperature of the refrigerant exiting the outlet port). That is, the control circuitry 100 determines the position of the expansion device 78 to obtain a flow of refrigerant such that the amount of superheat of the refrigerant at the outlet of the evaporator 80 and/or the inlet of the compressor 74 reaches the target superheat. can be adjusted. In addition, the control circuitry 100 may adjust the position of the expansion device 78 to reach a flow rate of the refrigerant that causes the temperature of the refrigerant discharged from the compressor 74 to reach a target discharge temperature. Control circuitry 100 may include a controller 104, such as a microcontroller. The controller 104 may include a processor 106 operatively coupled to the memory 108 to execute software, such as software for controlling the position of the inflation device 78 . Moreover, processor 106 may include multiple processors, one or more “general purpose” microprocessors, one or more special purpose microprocessors and/or one or more application specific integrated circuits (ASICS), or some combination thereof. For example, the processor 106 may include one or more reduced instruction set (RISC) processors, an advanced RISC machine (ARM) processor, an enhanced performance optimization to RISC (PowerPC) processor, a field programmable gate array (FPGA) integrated circuit, a graphics processing unit (GPU) or any other suitable processing device.

Memory 108 may include volatile memory, such as random access memory (RAM), non-volatile memory, such as read-only memory (ROM), flash memory, or any combination thereof. Memory 108 may store a variety of information that may be used for a variety of purposes. For example, the memory 108 may store processor-executable instructions (eg, firmware or software) for the processors 106 to execute, such as instructions for controlling the inflation device 78 .

The processor 106 may execute instructions to receive one or more signals from one or more sensors of the vapor compression system 72 . For example, control circuitry 100 (eg, a control system) may include sensors 110 , 112 , 114 , 116 and/or 118 located on or around various components of vapor compression system 72 . may include For example, the control circuitry 100 may include a temperature sensor 110 and a pressure sensor 112 located on the outlet of the evaporator 80 . As the refrigerant leaves the evaporator 80 , the temperature sensor 110 may transmit a signal indicating the temperature of the refrigerant to the controller 104 . Likewise, the pressure sensor 112 may send a signal to the controller 104 indicative of the pressure of the refrigerant leaving the evaporator 80 . Processor 106 receives respective signals from temperature sensor 110 and pressure sensor 112 as the refrigerant exits evaporator 80 (and/or enters compressor 74), It is possible to determine the superheat, and the superheat of the refrigerant represents the amount of heat of the refrigerant relative to the saturation point of the refrigerant. For example, the processor 106 may be stored in a memory 108 that defines the relationship of superheat to the pressure and temperature of the refrigerant at the outlet of the evaporator 80 (and/or at the inlet of the compressor 74 ). A lookup table can be used to determine overheating. The lookup table may be based on the physical properties of the refrigerant (eg, saturation point, amount, etc.).

In addition, the control circuitry 100 may include a temperature sensor 114 (eg, a second temperature sensor) that monitors the temperature of the refrigerant discharged from the compressor 74 . Accordingly, the processor 106 may determine a discharge temperature of the refrigerant from the compressor 74 and compare the discharge temperature to a threshold temperature, a predetermined temperature range, or a combination thereof. Additionally or alternatively, the control circuitry 100 includes a temperature sensor 116 (eg, a third temperature sensor) that monitors a temperature of a motor 94 configured to drive the compressor 74 . can do. Accordingly, the processor 106 may determine a motor temperature and compare the motor temperature to a threshold motor temperature, a predetermined motor temperature range, or a combination thereof. In some embodiments, an ambient temperature sensor 118 may be located proximate the vapor compression system 72 to detect the temperature of the ambient air. Although sensors 110 , 112 , 114 , 116 and/or 118 are described in detail, any suitable sensor that detects operating conditions of vapor compression system 72 may be used.

The processor 106 may receive one or more signals indicative of operating conditions (eg, temperature, pressure, vibration, etc.) of the vapor compression system 72 . The processor 106 may then be configured to initiate and/or utilize control modules of the processor 106 based on one or more signals indicative of operating conditions of the vapor compression system 72 . For example, processor 106 may generate a predetermined amount of superheat (e.g., target overheat or setpoint overheat) of refrigerant leaving evaporator 80 (and/or entering compressor 74) into evaporator 80 can be compared with the measured amount of superheat of refrigerant leaving (and/or entering compressor 74 ). In addition, the processor 106 may compare a predetermined discharge temperature (eg, a target discharge temperature or setpoint discharge temperature) of the refrigerant exiting the compressor 74 to a measured discharge temperature of the refrigerant exiting the compressor 74 . there is. The processor 106 may then determine an appropriate control module to utilize and/or activate based on the comparisons performed by the processor 106 .

When the processor 106 is operating under a first control module (eg, suction overheat control), the processor 106 measures and targets the overheating of the refrigerant leaving the evaporator 80 and/or entering the compressor 74 . Adjust the inflation device 78 based on the difference between overheating. For example, measure that the target superheat is 10 degrees Fahrenheit (°F) above the saturation point of the refrigerant (eg, based on the temperature and pressure of the refrigerant exiting the evaporator 80 and/or entering the compressor 74) If the resulting superheat is 5°F above the saturation point, the processor 106 may transmit a signal to the actuator 120 (eg, a motor or stepper motor) of the inflation device 78 to adjust the position of the inflation device 78 . can Accordingly, the position of the expansion device 78 can be adjusted to reduce the flow rate of the refrigerant directed to the evaporator 80, thereby increasing the amount of superheat of the refrigerant, ultimately achieving a target superheat of 10°F.

In addition, when the processor 106 operates under a second control module (eg, discharge temperature control), the processor 106 controls the difference between the measured discharge temperature and the target discharge temperature of the refrigerant exiting the compressor 74 . Adjust the inflation device 78 based on For example, when the target exhaust temperature is 175°F and the measured exhaust temperature is 160°F, the processor 106 adjusts the position of the inflation device 78 via the actuator 120 . Accordingly, the position of the expansion device 78 is adjusted to decrease the flow rate of the refrigerant through the compressor 74 and increase the temperature of the refrigerant discharged from the compressor 74 . In addition, in some embodiments, the processor 106 (eg, as measured by the sensor 116 ) in addition to or instead of adjusting the position of the expansion device 78 based on the outlet temperature of the refrigerant. The position of the expansion device 78 may be adjusted based on the temperature of the motor 94 driving the compressor 74 .

The controller 104 may include one or more proportional-integral-derivative (PID) controllers, fuzzy logic controllers, or any other control modules that adjust the expansion device 78 to achieve a target superheat, target exhaust temperature, and/or target motor temperature. other suitable controllers 104 of The controller 104 may be configured with various control modules (eg, an intake overheat control module, an exhaust temperature control module and/or motor temperature control module).

For example, FIG. 4 is a block diagram of a flowchart 140 illustrating the logic performed by the controller 104 operating and switching between control modules. For example, at block 142, compressor 74 is inactive (eg, powered off or not running). Accordingly, the vapor compression system 72 may not circulate the refrigerant. Accordingly, the expansion device 78 is not adjusted to control the flow rate of the refrigerant to the evaporator 80 as the refrigerant is not circulated through the vapor compression system 72 through the compressor 74 .

At block 144 , the start-up sequence of compressor 74 may be initiated, and controller 104 operates under first control module 146 (eg, suction overheat control). For example, the first control module 146 may include a startup sequence, whereby the controller 104 may have a predetermined amount of time (eg, 1 second, 2 seconds, 3 seconds, 4 seconds, 5 seconds). or more than 5 seconds) to the inflation device 78 to adjust the position of the inflation device 78 to the starting position. For example, when the expansion device 78 is in the starting position, the expansion device 78 pumps the refrigerant at a relatively high flow rate to the vapor compression system 72 so that the vapor compression system 72 can quickly reach steady state operation. ) can make it possible to cycle through

When the predetermined amount of time has elapsed for the starting position of the inflation device 78 , the controller 104 may pass the intake overheat control ramp of the first control module 146 at block 148 . For example, when vapor compression system 72 reaches substantially normal state operation, controller 104 leaves evaporator 80 and enters compressor 74 (eg, the suction port of compressor 74 ). Adjust the expansion device 78 so that the overheating of the refrigerant reaches the target overheating. Accordingly, the controller 104 sends a second signal to the inflation device 78 that adjusts the position of the inflation device 78 based on feedback received from the sensors 110 , 112 , 114 , 116 and/or 118 . send In some embodiments, the controller 104 directs the expansion device 78 to a command position based on a threshold position (eg, a predetermined position that circulates a minimum amount of refrigerant through the vapor compression system 72 ) or target overheating. is configured to adjust. For example, the command position is determined by the controller 104 as the position of the expansion device 78 that enables superheat of the refrigerant leaving the evaporator 80 and entering the compressor 74 to reach a target superheat. The controller 104 compares the critical position to the command position and selects a position corresponding to a faster flow rate of refrigerant through the vapor compression system 72 . That is, the controller 104 may correlate the position of the expansion device 78 with a value proportional to the flow rate of the refrigerant through the vapor compression system 72 . Accordingly, the controller 104 selects a position (eg, a threshold position or a command position) comprising a higher value such that the refrigerant is not blocked from circulating through the vapor compression system 72 .

Moreover, if the measured overheating of the refrigerant reaches the target overheating, the controller 104 may operate under the suction overheating control of the first control module 146 at block 150 . In some embodiments, the intake overheat control may be similar to the intake overheat control ramp as shown in block 148 with less adjustment to the position of the inflation device 78 (eg, intake overheat control). The ramp can make relatively many adjustments to the position of the inflation device 78 to quickly reach the target overheat). That is, the suction overheat control at block 150 is utilized to maintain the measured overheat of the refrigerant leaving the evaporator 80 and entering the compressor 74 as the target overheat. Accordingly, relatively few adjustments are made to the inflation device 78 during intake overheat control at block 150 .

During the intake overheat control at block 150 , the controller 104 is configured to adjust the position of the inflation device 78 based on feedback received from the sensors 110 , 112 , 114 , 116 and/or 118 . A signal is sent to the inflation device 78 . The controller 104 is configured to adjust the expansion device 78 to a command position based on a threshold position (eg, a predetermined position that circulates a minimum amount of refrigerant through the vapor compression system 72 ) or a target overheating. In some embodiments, the threshold position of the intake overheat control of block 150 is the same as the threshold position of the intake overheat control ramp of block 148 . However, in other embodiments, the threshold position of the intake overheat control of block 150 is different from the threshold position of the intake overheat control ramp of block 148 . In any case, the command position is determined by the controller 104 as the position of the expansion device 78 that enables superheat of the refrigerant leaving the evaporator 80 and entering the compressor 74 to reach the target superheat. . The controller 104 compares the critical position to the command position and places a position (or vapor) corresponding to a faster flow rate of the refrigerant through the vapor compression system 72 such that the refrigerant is not blocked from circulating through the vapor compression system 72 . a higher value corresponding to the flow rate of the refrigerant through the compression system 72) is selected.

As previously discussed, the controller 104 controls the first control module 146 based on operating parameters of the vapor compression system 72 monitored by the sensors 110 , 112 , 114 , 116 and/or 118 . and the second control module 152 . For example, the controller 104 may control the amount of refrigerant leaving the compressor 74 (eg, as measured by the sensor 114 ) from the first control module 146 (eg, suction superheat control). It may be configured to switch to the second control module 152 (eg, control the exhaust temperature) based at least on the exhaust temperature. The controller 104 may compare the measured exhaust temperature from the sensor 114 to one or more exhaust temperature thresholds stored in the memory 108 of the controller 104 . In some embodiments, the controller 104 determines that the measured exhaust temperature is the first exhaust temperature for a predetermined amount of time (eg, greater than 1 second, 2 seconds, 3 seconds, 4 seconds, 5 seconds, or 5 seconds). When the threshold is exceeded, it switches from the first control module 146 to the second control module 152 . In addition, the controller is configured to send the second control module ( 152) can be configured to be converted immediately. In some embodiments, the amount of offset between the first exhaust temperature threshold and the second exhaust temperature threshold is between 5°F and 50°F, between 7°F and 25°F, or between 8°F and 15°F.

When the controller 104 operates under the second control module 152 , the controller 104 controls the expansion device 78 based on the measured exhaust temperature to achieve the target exhaust temperature as shown in block 154 . Adjust the position. For example, when the measured exhaust temperature is below the target exhaust temperature, the controller 104 sends a signal to adjust the position of the expansion device 78 to reduce the flow of refrigerant through the vapor compression system 72 . (For example, reducing the flow of refrigerant through the evaporator 80 increases the temperature of the refrigerant exiting the compressor 74). Likewise, when the measured exhaust temperature exceeds the target exhaust temperature, the controller 104 sends a signal to adjust the position of the expansion device 78 to increase the flow of refrigeration through the vapor compression system 72 (eg For example, increasing the flow of refrigerant through the evaporator 80 reduces the temperature of the refrigerant exiting the compressor 74). In other embodiments as discussed above, the second control module 152 controls the expansion device 78 based on the temperature of the motor 94 in addition to or instead of the discharge temperature of the refrigerant from the compressor 74 . position can be adjusted.

As previously discussed, the signal transmitted from the controller 104 is a command position based on a threshold position (eg, a predetermined position that circulates a minimum amount of refrigerant through the vapor compression system 72) and the measured exhaust temperature. a position of the inflation device 78 selected from In some embodiments, the threshold position of the exhaust temperature control at block 154 is the same as or different from the threshold position of the intake superheat ramp control at block 148 and/or the intake overheat control at block 150 . The command position is determined by the controller 104 as the position of the expansion device 78 that enables the discharge temperature of the refrigerant leaving the compressor 74 to reach the target discharge temperature. The controller 104 compares the critical position to the command position and selects a position corresponding to a faster flow rate of refrigerant through the vapor compression system 72 . That is, the controller 104 may correlate the position of the expansion device 78 with a value proportional to the flow rate of the refrigerant through the vapor compression system 72 . Accordingly, the controller 104 selects a position (eg, a threshold position or a command position) comprising a higher value such that the refrigerant is not blocked from circulating through the vapor compression system 72 .

In some embodiments, the second control module 152 overrides the first control module 146 (eg, ignores suction overheating). For example, in some cases adjusting the inflation device 78 to achieve a target exhaust temperature causes the intake overheat to decrease below a predetermined amount. Accordingly, the controller 104 ignores the first control module 146 despite the fact that the overheating of the refrigerant is below the target overheating.

In addition, the controller 104 receives feedback from the sensors 110 and 112 indicative of the temperature and pressure of the refrigerant leaving the evaporator 80 (and/or entering the compressor 74 ). As previously discussed, the temperature and pressure of the refrigerant leaving the evaporator 80 (and/or entering the compressor 74 ) may be utilized to determine the amount of superheat of the refrigerant. The controller 104 determines that the measured amount of overheat (eg, as determined from feedback from sensors 110 and 112 ) is a predetermined amount of time (eg, 1 second, 2 seconds, 3 seconds, 4 seconds). second control module 152 to first control module 146 (eg, block 154 to block 150 ) when the first overheat threshold is exceeded for seconds, 5 seconds, or more than 5 seconds ) can be converted. In addition, the controller 104 is configured to control the first control module 146 from the second control module 152 when the measured amount of overheating exceeds a second overheating threshold, and the second overheating threshold is greater than the first overheating threshold. can be converted immediately to The controller 104 then operates under the first control module 146 and an expansion device 78 based on the measured amount of superheat of the refrigerant leaving the evaporator 80 (and/or entering the compressor 74). position can be adjusted.

As indicated above, embodiments of the present invention may provide one or more technical effects useful in the operation of HVAC systems to improve the efficiency of the compressor. For example, embodiments of the present invention relate to controlling the position of an electronic expansion valve based on the amount of superheat of the refrigerant leaving the evaporator and/or the refrigerant entering the compressor as well as the discharge temperature of the refrigerant leaving the compressor. Control of the electronic expansion valve allows the operating temperatures of the refrigerant through the compressor to be adjusted without utilizing a liquid injection system that directs liquid refrigerant droplets to the compressor. Removal and/or reduction of liquid droplets within the compressor improves the efficiency of the compressor and, therefore, improves the operation of the HVAC system. The technical effects and technical problems in this specification are examples and are not limiting. It should be noted that the embodiments described herein may have other technical effects and solve other technical problems.

While only specific features and embodiments have been illustrated and described, many modifications and changes (eg, the size of various elements) without departing materially from the novel teachings and advantages of the subject matter recited in the claims , variations in dimensions, structure, shape and proportions, values of parameters (eg, temperature, pressure, etc.), mounting arrangement, use of materials, colors, orientations, etc.) may occur to those skilled in the art. The order or sequence of any process or method steps may be varied or rearranged according to alternative embodiments. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and variations that fall within the scope of the true spirit of the present invention. Moreover, in an effort to provide a concise description of example embodiments, not all features of an actual implementation (ie, those not relevant to the presently contemplated best mode, or those not relevant to feasibility of implementation) may not have been described. It should be understood that in the development of any such actual implementation, such as in any engineering or design scheme, many implementation specific decisions may be made. Such development efforts may be complex and time consuming, but would nevertheless be a routine undertaking to design, manufacture, and manufacture for those skilled in the art having the benefit of the present invention without undue experimentation.

Claims (20)

As a heating, ventilation and air conditioning (HVAC) system:
a vapor compression system comprising a refrigerant;
a compressor of the vapor compression system configured to circulate the refrigerant through the vapor compression system;
an expansion device of the vapor compression system configured to regulate a flow of the refrigerant through the vapor compression system; and
including a controller;
the controller is configured to operate in accordance with a first control module for adjusting a position of the expansion device based on a measured amount of superheat of the refrigerant entering the compressor to achieve a target amount of superheat;
the controller is configured to operate in accordance with a second control module for adjusting a position of the expansion device based on a measured discharge temperature of the refrigerant leaving the compressor to achieve a target discharge temperature;
The controller is configured to determine that the measured discharge temperature of the refrigerant leaving the compressor exceeds a first discharge temperature threshold for a predetermined amount of time or the measured discharge temperature of the refrigerant leaving the compressor exceeds a second discharge temperature threshold. when exceeded, the HVAC system is configured to switch from the first control module to the second control module, wherein the second exhaust temperature threshold is greater than the first exhaust temperature threshold. delete delete delete According to claim 1,
The controller is configured such that the measured amount of superheat of the refrigerant entering the compressor exceeds a first overheat threshold for a predetermined amount of time or that the measured amount of overheat of the refrigerant entering the compressor exceeds a second overheat threshold and to switch from the second control module to the first control module, the second overheat threshold being greater than the first overheating threshold. According to claim 1,
the controller is configured to, when operating under the first control module, transmit a signal to adjust the position of the expansion device, the signal being configured to transmit a signal based on the measured amount of the superheat of the refrigerant entering the compressor An HVAC system comprising a critical position of an expansion device or a command position of the expansion device, either of which enables faster flow of refrigerant through the expansion device. According to claim 1,
the controller is configured to, when operating under the second control module, transmit a signal to adjust the position of the expansion device, wherein the signal is configured to adjust the position of the expansion device based on the measured discharge temperature of the refrigerant leaving the compressor. a critical position of or a command position of the expansion device, either of which enables a faster flow of refrigerant through the expansion device. According to claim 1,
and the controller is configured to operate under the first control module during startup of the compressor. According to claim 1,
wherein the expansion device is an electronic expansion valve. According to claim 1,
and a motor configured to drive the compressor, wherein the controller is configured to adjust the position of the expansion device based on the measured motor temperature of the motor to achieve a target motor temperature. instructions to receive first feedback indicative of a temperature and pressure of refrigerant entering a compressor of the vapor compression system;
instructions to use the temperature and the pressure of the refrigerant entering the compressor of the vapor compression system to determine a measured amount of superheat of the refrigerant entering the compressor of the vapor compression system;
instructions to receive second feedback indicative of a discharge temperature of the refrigerant leaving the compressor of the vapor compression system;
command to use a first control module or a second control module to adjust a position of an expansion device of the vapor compression system, wherein the first control module measures overheating of refrigerant entering the compressor to achieve a target amount of overheating instructions configured to adjust the expansion device based on the determined amount, the second control module being configured to adjust the expansion device based on the discharge temperature of the refrigerant leaving the compressor to achieve a target discharge temperature; and
from the first control module when the discharge temperature of the refrigerant leaving the compressor exceeds a first discharge temperature threshold for a predetermined amount of time or when the discharge temperature of the refrigerant leaving the compressor exceeds a second discharge temperature threshold one or more tangible non-transitory machine comprising processor-executable instructions of: instructions to switch to the second control module, wherein the second exhaust temperature threshold is greater than the first exhaust temperature threshold; readable medium. delete delete delete 12. The method of claim 11,
The processor-executable instructions indicate that the measured amount of superheat of the refrigerant entering the compressor exceeds a first overheat threshold for a predetermined amount of time or that the measured amount of superheat of the refrigerant entering the compressor is a second one or more tangible non-transitory machine-readable media configured to switch from the second control module to the first control module when two overheat thresholds are exceeded, wherein the second overheat threshold is greater than the first overheat threshold . receiving first feedback indicative of a temperature and pressure of refrigerant entering a compressor of a vapor compression system;
determining a measured amount of superheat of the refrigerant entering the compressor of the vapor compression system using the temperature and the pressure of the refrigerant entering the compressor of the vapor compression system;
receiving second feedback indicative of a discharge temperature of the refrigerant leaving the compressor of the vapor compression system;
adjusting a position of an expansion device of the vapor compression system using a first control module and a second control module, wherein the first control module controls the amount of overheating of the refrigerant entering the compressor to achieve a target amount of overheating; configured to adjust the expansion device based on the measured amount, wherein the second control module is configured to adjust the expansion device based on a discharge temperature of refrigerant leaving the compressor to achieve a target discharge temperature; and
the first control when the discharge temperature of the refrigerant leaving the compressor exceeds a first discharge temperature threshold for a predetermined amount of time or when the discharge temperature of the refrigerant leaving the compressor exceeds a second discharge temperature threshold transitioning from a module to the second control module, wherein the second exhaust temperature threshold is greater than the first exhaust temperature threshold. delete delete delete 17. The method of claim 16,
the measured amount of superheat of the refrigerant entering the compressor exceeds a first overheat threshold for a predetermined amount of time or the measured amount of overheat of the refrigerant entering the compressor exceeds a second overheat threshold when switching from the second control module to the first control module, wherein the second overheat threshold is greater than the first overheat threshold.

Images